This invention relates in general to highways and in particular to highway markings.
With the steady increase in the number of motor vehicles, highways are becoming more congested. At the same time, continual design improvements have resulted in significant ride and sound deadening enhancements to motor vehicles, while available engine horsepower has generally increased. Such improvements in the vehicles may result in higher speed operation without the operator sensing the increased speed. As a result, vehicle operators need to be increasingly attentive to the traffic conditions surrounding their vehicles. Nevertheless, drivers are known to follow other vehicles too closely, especially during rush hour traffic conditions, which can lead to multiple vehicle accidents.
In the past, many beginning vehicle operators have been taught to use a car-length rule for establishing a following distance for the vehicle immediately ahead. The car-length rule provides a space between the operator's vehicle and the vehicle ahead of one car length for every ten mph on the speedometer of the operator's vehicle. However, the car-length rule is no longer recommended because car lengths are difficult to estimate, nearly impossible to visualize when moving, and the rule may not provide enough space. For example, under the rule, six car lengths at 60 mph provides roughly 108 feet of space. At 60 mph, the reaction time for an alert vehicle operator consumes 60 to 130 feet. For a typical vehicle operator, who is often distracted by other factors such a cell phone or the broadcast being received over his vehicle radio, the reaction time may consume closer to 135 feet. Thus, with the car-length rule, after the vehicle operator reacts to the action of the vehicle ahead, there may be little or no time left to act.
Because of the problems described above, the car-length rule has generally been replaced by a two second rule that states that a vehicle operator should maintain at least two seconds of following distance. Application of the two second rule requires that the vehicle operator note when the vehicle immediately ahead passes an object, such as a sign post and then mentally count the elapsed time before his vehicle passes the same object. If less than two seconds pass, the operator does not have adequate space between his vehicle and the one ahead. Two seconds of following distance at 60 mph provides over 176 feet of pavement to react and respond. While it is necessary for the operator to respond quickly, it can be done under normal circumstances. However, application of the two second rule may be cumbersome and distracting to the vehicle operator. At best, the two second rule is applied intermittently (if at all) while driving. Accordingly, it would be desirable to provide a simple device to aid vehicle operators in maintaining spacing between their own and other vehicles on a continuous basis.